Sensitivity and spatial resolution of transient pressure and tracer data for heterogeneity characterization

This paper examines the sensitivities of interwell tracer and transient pressure response to spatial distribution of permeability heterogeneity. Based on the sensitivities, we describe a formalism to quantify the spatial resolution and averaging (smearing) associated with estimates of permeabilities derived through inversion of tracer and/or pressure data. The spatial resolution is a measure of the effectiveness of the data in estimating local-scale (grid block) permeabilities. The averaging kernels quantify the inherent averaging associated with our estimates due to limited data or sampling. By examining the spatial resolution and averaging kernels as a function of various data types, we can quantitatively evaluate the relative importance of tracer versus pressure data for heterogeneity characterization and the improvement in estimates obtained by combining the data types. We illustrate the concepts by application to a quarter five-spot geometry and also to an experimental tracer response from a well-characterized slab of Antolini sandstone. Tracer data is found to yield much better resolution compared to transient pressure response. Also, both transient pressure data and tracer data appear to better resolve barriers to flow rather than channels to flow.

Sensitivity and spatial resolution of transient pressure and tracer data for heterogeneity characterization Conference Paper